The present invention relates to the field of outdoor surface treatments. More particularly, the invention relates to outdoor surface treatments used as ground cover below play equipment or athletic fields.
Numerous surface treatments for athletic fields, playgrounds, and other play areas are known in the art. Many prior art surface treatments have addressed the need to provide a surface treatment which is durable, adequately provides drainage, and also provides a degree of safety to participants who may come in violent contact with the surface treatment.
U.S. Pat. No. 3,801,421 discloses a resilient composite useful as surfacing for athletic fields. The surface material is essentially a vulcanized rubber treated with isocyanate. However, an entire outdoor surfacing treatment is not disclosed, just a surfacing material made of particulate vulcanized rubber which is bonded with an isocyanate resin.
U.S. Pat. No. 5,182,137 discloses a method of applying a bound particulate rubber outdoor surface. This invention addresses the method of laying down a track surface similar to those used in track and field events. However, it does not address the concern that differing the types of materials used for the surface will change the types of activities for which surfacing treatments should be used.
U.S. Pat. No. 3,022,712 discloses a shock absorbing structure. The shock absorbing structure consists of a layered cushion, not a flooring or an outdoor surface treatment. As such, the structure disclosed therein does not address the needs of an outdoor surface treatment.
U.S. Pat. No. 4,564,310 discloses a resilient paving composition for playfields, sportsfields, and recreation areas. This composition is composed from top to bottom as follows: a topping layer followed by a combination of latex and vulcanized scrap rubber; followed by a layer of fibrous vulcanized scrap rubber without latex; and, a mineral aggregate as a base material. However, the topping layer is composed of about 70% vulcanized rubber particles, zinc oxide in about 1-7% of weight, and 25% rubber latex. The use of vulcanized rubber particles, although providing a certain thermal stability, may in fact be too hard for some uses.
U.S. Pat. No. 3,446,122 discloses an elastic surface for sports grounds, playgrounds, and footpaths. The surface disclosed consists of from top to bottom: a water permeable top layer, a fibrous bottom layer, and an elastic middle layer composed of plastic spheres. Although this surface provides the requisite drainage for an outdoor surface treatment, it does not address the need for adequate protection from injuries occurring when participants make violent contact with the surface.